Electrophotographic image forming apparatuses, such as copiers, printers, facsimile machines, or multifunction peripherals having functions of copiers, printers and facsimile machines, generally form images by causing developing devices to form toner images with developer called toner or carrier. In such image forming apparatuses, toner is consumed through image formation; therefore, in general, toner cartridges containing toner are attached to the image forming apparatuses and when the toner cartridges become empty of the toner, the toner cartridges are replaced with new ones in order to replenish new toner.
In a toner supply system using the cartridges as described above, there is a user's demand to use up all toner in the cartridges in order to reduce running costs. Therefore, various methods have been employed, such as a method in which what is called a screw bottle that is a cylindrical container provided with an inner-mounted spiral protrusion is used as a toner cartridge and toner is gradually conveyed to a discharging unit by rotating the container, or a method in which a screw typically called an auger is provided inside the container and toner is conveyed to a discharging unit by rotating the screw.
In the conveying system using the auger, it is needed to arrange and rotate the screw inside the container, so that the configuration becomes complicated. Furthermore, in this conveying system, because a stack of toner is forcibly conveyed by the auger, load is applied to the toner and the toner may be aggregated or deteriorated. Moreover, arranging the screw inside the container that is a replaceable part leads to increase in costs of consumables, so that environmental loads increase because of resource consumption.
On the other hand, in the conveying system using the screw bottle, it is not needed to arrange a screw inside the container. Therefore, the configuration becomes simple. However, in this conveying system, because the container itself is rotated when it is used, the container usually has a shape of a cylinder with an outlet arranged on one side surface of the body thereof (a shape like a bottle being laid down). Therefore, the container is disadvantageous in that the capacity for housing toner becomes smaller than a container in a rectangular-solid shape or the container may be too slippery for a person to hold when the container is replaced.
Alternatively, as a toner conveying system that does not use the screw bottle and the auger, there is a method in which a container is caused to oscillate (reciprocating movement) by applying shock to the container from outside or by bringing the container into contact with a stopper so that toner can be moved and discharged with the aid of the inertia force thereof (see Japanese Laid-open Patent Publication No. 2002-46843). In this system, when a large amount of toner is contained, the toner stacked in the container collectively moves by the oscillation, so that a satisfactory toner conveying speed can be assured per reciprocating oscillation. However, as the amount of toner in the container decreases, a stack of the toner collapses and the toner is thinly spread, so that the toner conveying speed per reciprocating oscillation decreases with a decrease in the height of the stack of the toner. Therefore, the conveying speed cannot be maintained. Furthermore, a writing system may be influenced by the oscillation of the container and image distortion may occur. Moreover, it takes a long time to fluidize the toner or the toner may be aggregated (blocked) due to an action similar to tapping that occurs by the oscillation.
Further, as a conveying type different from the respective conveying types, there is proposed a type in which a deformable container is used and a convex member is pressed and moved from the outside of the container so as to deliver a toner therein (see Patent Literature 2). According to such a conveying type, the toner may be conveyed with a small stress. Then, the aggregation or the degradation of the toner may be suppressed and there is a low possibility that an abnormal image may be generated by a large vibration or an impact.
Patent Literature 1: Japanese Patent Application Laid-open No. 2002-46843
Patent Literature 2: Japanese Patent Application Laid-open No. 11-143195